/*
* "$Id: mxml-index.c 426 2011-01-01 23:42:17Z mike $"
*
* Index support code for Mini-XML, a small XML-like file parsing library.
*
* Copyright 2003-2011 by Michael R Sweet.
*
* These coded instructions, statements, and computer programs are the
* property of Michael R Sweet and are protected by Federal copyright
* law.  Distribution and use rights are outlined in the file "COPYING"
* which should have been included with this file.  If this file is
* missing or damaged, see the license at:
*
*     http://www.minixml.org/
*
* Contents:
*
*/

/*
* Include necessary headers...
*/

#include "mxml-config.h"
#include "mxml.h"


/*
* Sort functions...
*/

static int	index_compare(mxml_index_t *ind, mxml_node_t *first,
	mxml_node_t *second);
static int	index_find(mxml_index_t *ind, const char *element,
	const char *value, mxml_node_t *node);
static void	index_sort(mxml_index_t *ind, int left, int right);


/*
* 'mxmlIndexDelete()' - Delete an index.
*/

void
	mxmlIndexDelete(mxml_index_t *ind)	/* I - Index to delete */
{
	/*
	* Range check input..
	*/

	if (!ind)
		return;

	/*
	* Free memory...
	*/

	if (ind->attr)
		free(ind->attr);

	if (ind->alloc_nodes)
		free(ind->nodes);

	free(ind);
}


/*
* 'mxmlIndexEnum()' - Return the next node in the index.
*
* Nodes are returned in the sorted order of the index.
*/

mxml_node_t *				/* O - Next node or NULL if there is none */
	mxmlIndexEnum(mxml_index_t *ind)	/* I - Index to enumerate */
{
	/*
	* Range check input...
	*/

	if (!ind)
		return (NULL);

	/*
	* Return the next node...
	*/

	if (ind->cur_node < ind->num_nodes)
		return (ind->nodes[ind->cur_node ++]);
	else
		return (NULL);
}


/*
* 'mxmlIndexFind()' - Find the next matching node.
*
* You should call mxmlIndexReset() prior to using this function for
* the first time with a particular set of "element" and "value"
* strings. Passing NULL for both "element" and "value" is equivalent
* to calling mxmlIndexEnum().
*/

mxml_node_t *				/* O - Node or NULL if none found */
	mxmlIndexFind(mxml_index_t *ind,	/* I - Index to search */
	const char   *element,	/* I - Element name to find, if any */
	const char   *value)	/* I - Attribute value, if any */
{
	int		diff,			/* Difference between names */
		current,		/* Current entity in search */
		first,			/* First entity in search */
		last;			/* Last entity in search */


#ifdef DEBUG
	printf("mxmlIndexFind(ind=%p, element=\"%s\", value=\"%s\")\n",
		ind, element ? element : "(null)", value ? value : "(null)");
#endif /* DEBUG */

	/*
	* Range check input...
	*/

	if (!ind || (!ind->attr && value))
	{
#ifdef DEBUG
		puts("    returning NULL...");
		printf("    ind->attr=\"%s\"\n", ind->attr ? ind->attr : "(null)");
#endif /* DEBUG */

		return (NULL);
	}

	/*
	* If both element and value are NULL, just enumerate the nodes in the
	* index...
	*/

	if (!element && !value)
		return (mxmlIndexEnum(ind));

	/*
	* If there are no nodes in the index, return NULL...
	*/

	if (!ind->num_nodes)
	{
#ifdef DEBUG
		puts("    returning NULL...");
		puts("    no nodes!");
#endif /* DEBUG */

		return (NULL);
	}

	/*
	* If cur_node == 0, then find the first matching node...
	*/

	if (ind->cur_node == 0)
	{
		/*
		* Find the first node using a modified binary search algorithm...
		*/

		first = 0;
		last  = ind->num_nodes - 1;

#ifdef DEBUG
		printf("    find first time, num_nodes=%d...\n", ind->num_nodes);
#endif /* DEBUG */

		while ((last - first) > 1)
		{
			current = (first + last) / 2;

#ifdef DEBUG
			printf("    first=%d, last=%d, current=%d\n", first, last, current);
#endif /* DEBUG */

			if ((diff = index_find(ind, element, value, ind->nodes[current])) == 0)
			{
				/*
				* Found a match, move back to find the first...
				*/

#ifdef DEBUG
				puts("    match!");
#endif /* DEBUG */

				while (current > 0 &&
					!index_find(ind, element, value, ind->nodes[current - 1]))
					current --;

#ifdef DEBUG
				printf("    returning first match=%d\n", current);
#endif /* DEBUG */

				/*
				* Return the first match and save the index to the next...
				*/

				ind->cur_node = current + 1;

				return (ind->nodes[current]);
			}
			else if (diff < 0)
				last = current;
			else
				first = current;

#ifdef DEBUG
			printf("    diff=%d\n", diff);
#endif /* DEBUG */
		}

		/*
		* If we get this far, then we found exactly 0 or 1 matches...
		*/

		for (current = first; current <= last; current ++)
			if (!index_find(ind, element, value, ind->nodes[current]))
			{
				/*
				* Found exactly one (or possibly two) match...
				*/

#ifdef DEBUG
				printf("    returning only match %d...\n", current);
#endif /* DEBUG */

				ind->cur_node = current + 1;

				return (ind->nodes[current]);
			}

			/*
			* No matches...
			*/

			ind->cur_node = ind->num_nodes;

#ifdef DEBUG
			puts("    returning NULL...");
#endif /* DEBUG */

			return (NULL);
	}
	else if (ind->cur_node < ind->num_nodes &&
		!index_find(ind, element, value, ind->nodes[ind->cur_node]))
	{
		/*
		* Return the next matching node...
		*/

#ifdef DEBUG
		printf("    returning next match %d...\n", ind->cur_node);
#endif /* DEBUG */

		return (ind->nodes[ind->cur_node ++]);
	}

	/*
	* If we get this far, then we have no matches...
	*/

	ind->cur_node = ind->num_nodes;

#ifdef DEBUG
	puts("    returning NULL...");
#endif /* DEBUG */

	return (NULL);
}


/*
* 'mxmlIndexGetCount()' - Get the number of nodes in an index.
*
* @since Mini-XML 2.7@
*/

int					/* I - Number of nodes in index */
	mxmlIndexGetCount(mxml_index_t *ind)	/* I - Index of nodes */
{
	/*
	* Range check input...
	*/

	if (!ind)
		return (0);

	/*
	* Return the number of nodes in the index...
	*/

	return (ind->num_nodes);
}


/*
* 'mxmlIndexNew()' - Create a new index.
*
* The index will contain all nodes that contain the named element and/or
* attribute. If both "element" and "attr" are NULL, then the index will
* contain a sorted list of the elements in the node tree.  Nodes are
* sorted by element name and optionally by attribute value if the "attr"
* argument is not NULL.
*/

mxml_index_t *				/* O - New index */
	mxmlIndexNew(mxml_node_t *node,		/* I - XML node tree */
	const char  *element,	/* I - Element to index or NULL for all */
	const char  *attr)		/* I - Attribute to index or NULL for none */
{
	mxml_index_t	*ind;			/* New index */
	mxml_node_t	*current,		/* Current node in index */
		**temp;			/* Temporary node pointer array */


	/*
	* Range check input...
	*/

#ifdef DEBUG
	printf("mxmlIndexNew(node=%p, element=\"%s\", attr=\"%s\")\n",
		node, element ? element : "(null)", attr ? attr : "(null)");
#endif /* DEBUG */

	if (!node)
		return (NULL);

	/*
	* Create a new index...
	*/

	if ((ind = calloc(1, sizeof(mxml_index_t))) == NULL)
	{
		mxml_error("Unable to allocate %d bytes for index - %s",
			sizeof(mxml_index_t), strerror(errno));
		return (NULL);
	}

	if (attr)
		ind->attr = strdup(attr);

	if (!element && !attr)
		current = node;
	else
		current = mxmlFindElement(node, node, element, attr, NULL, MXML_DESCEND);

	while (current)
	{
		if (ind->num_nodes >= ind->alloc_nodes)
		{
			if (!ind->alloc_nodes)
				temp = malloc(64 * sizeof(mxml_node_t *));
			else
				temp = realloc(ind->nodes, (ind->alloc_nodes + 64) * sizeof(mxml_node_t *));

			if (!temp)
			{
				/*
				* Unable to allocate memory for the index, so abort...
				*/

				mxml_error("Unable to allocate %d bytes for index: %s",
					(ind->alloc_nodes + 64) * sizeof(mxml_node_t *),
					strerror(errno));

				mxmlIndexDelete(ind);
				return (NULL);
			}

			ind->nodes       = temp;
			ind->alloc_nodes += 64;
		}

		ind->nodes[ind->num_nodes ++] = current;

		current = mxmlFindElement(current, node, element, attr, NULL, MXML_DESCEND);
	}

	/*
	* Sort nodes based upon the search criteria...
	*/

#ifdef DEBUG
	{
		int i;				/* Looping var */


		printf("%d node(s) in index.\n\n", ind->num_nodes);

		if (attr)
		{
			printf("Node      Address   Element         %s\n", attr);
			puts("--------  --------  --------------  ------------------------------");

			for (i = 0; i < ind->num_nodes; i ++)
				printf("%8d  %-8p  %-14.14s  %s\n", i, ind->nodes[i],
				ind->nodes[i]->value.element.name,
				mxmlElementGetAttr(ind->nodes[i], attr));
		}
		else
		{
			puts("Node      Address   Element");
			puts("--------  --------  --------------");

			for (i = 0; i < ind->num_nodes; i ++)
				printf("%8d  %-8p  %s\n", i, ind->nodes[i],
				ind->nodes[i]->value.element.name);
		}

		putchar('\n');
	}
#endif /* DEBUG */

	if (ind->num_nodes > 1)
		index_sort(ind, 0, ind->num_nodes - 1);

#ifdef DEBUG
	{
		int i;				/* Looping var */


		puts("After sorting:\n");

		if (attr)
		{
			printf("Node      Address   Element         %s\n", attr);
			puts("--------  --------  --------------  ------------------------------");

			for (i = 0; i < ind->num_nodes; i ++)
				printf("%8d  %-8p  %-14.14s  %s\n", i, ind->nodes[i],
				ind->nodes[i]->value.element.name,
				mxmlElementGetAttr(ind->nodes[i], attr));
		}
		else
		{
			puts("Node      Address   Element");
			puts("--------  --------  --------------");

			for (i = 0; i < ind->num_nodes; i ++)
				printf("%8d  %-8p  %s\n", i, ind->nodes[i],
				ind->nodes[i]->value.element.name);
		}

		putchar('\n');
	}
#endif /* DEBUG */

	/*
	* Return the new index...
	*/

	return (ind);
}


/*
* 'mxmlIndexReset()' - Reset the enumeration/find pointer in the index and
*                      return the first node in the index.
*
* This function should be called prior to using mxmlIndexEnum() or
* mxmlIndexFind() for the first time.
*/

mxml_node_t *				/* O - First node or NULL if there is none */
	mxmlIndexReset(mxml_index_t *ind)	/* I - Index to reset */
{
#ifdef DEBUG
	printf("mxmlIndexReset(ind=%p)\n", ind);
#endif /* DEBUG */

	/*
	* Range check input...
	*/

	if (!ind)
		return (NULL);

	/*
	* Set the index to the first element...
	*/

	ind->cur_node = 0;

	/*
	* Return the first node...
	*/

	if (ind->num_nodes)
		return (ind->nodes[0]);
	else
		return (NULL);
}


/*
* 'index_compare()' - Compare two nodes.
*/

static int				/* O - Result of comparison */
	index_compare(mxml_index_t *ind,	/* I - Index */
	mxml_node_t  *first,	/* I - First node */
	mxml_node_t  *second)	/* I - Second node */
{
	int	diff;				/* Difference */


	/*
	* Check the element name...
	*/

	if ((diff = strcmp(first->value.element.name,
		second->value.element.name)) != 0)
		return (diff);

	/*
	* Check the attribute value...
	*/

	if (ind->attr)
	{
		if ((diff = strcmp(mxmlElementGetAttr(first, ind->attr),
			mxmlElementGetAttr(second, ind->attr))) != 0)
			return (diff);
	}

	/*
	* No difference, return 0...
	*/

	return (0);
}


/*
* 'index_find()' - Compare a node with index values.
*/

static int				/* O - Result of comparison */
	index_find(mxml_index_t *ind,		/* I - Index */
	const char   *element,	/* I - Element name or NULL */
	const char   *value,		/* I - Attribute value or NULL */
	mxml_node_t  *node)		/* I - Node */
{
	int	diff;				/* Difference */


	/*
	* Check the element name...
	*/

	if (element)
	{
		if ((diff = strcmp(element, node->value.element.name)) != 0)
			return (diff);
	}

	/*
	* Check the attribute value...
	*/

	if (value)
	{
		if ((diff = strcmp(value, mxmlElementGetAttr(node, ind->attr))) != 0)
			return (diff);
	}

	/*
	* No difference, return 0...
	*/

	return (0);
}


/*
* 'index_sort()' - Sort the nodes in the index...
*
* This function implements the classic quicksort algorithm...
*/

static void
	index_sort(mxml_index_t *ind,		/* I - Index to sort */
	int          left,		/* I - Left node in partition */
	int          right)		/* I - Right node in partition */
{
	mxml_node_t	*pivot,			/* Pivot node */
		*temp;			/* Swap node */
	int		templ,			/* Temporary left node */
		tempr;			/* Temporary right node */


	/*
	* Loop until we have sorted all the way to the right...
	*/

	do
	{
		/*
		* Sort the pivot in the current partition...
		*/

		pivot = ind->nodes[left];

		for (templ = left, tempr = right; templ < tempr;)
		{
			/*
			* Move left while left node <= pivot node...
			*/

			while ((templ < right) &&
				index_compare(ind, ind->nodes[templ], pivot) <= 0)
				templ ++;

			/*
			* Move right while right node > pivot node...
			*/

			while ((tempr > left) &&
				index_compare(ind, ind->nodes[tempr], pivot) > 0)
				tempr --;

			/*
			* Swap nodes if needed...
			*/

			if (templ < tempr)
			{
				temp              = ind->nodes[templ];
				ind->nodes[templ] = ind->nodes[tempr];
				ind->nodes[tempr] = temp;
			}
		}

		/*
		* When we get here, the right (tempr) node is the new position for the
		* pivot node...
		*/

		if (index_compare(ind, pivot, ind->nodes[tempr]) > 0)
		{
			ind->nodes[left]  = ind->nodes[tempr];
			ind->nodes[tempr] = pivot;
		}

		/*
		* Recursively sort the left partition as needed...
		*/

		if (left < (tempr - 1))
			index_sort(ind, left, tempr - 1);
	}
	while (right > (left = tempr + 1));
}


/*
* End of "$Id: mxml-index.c 426 2011-01-01 23:42:17Z mike $".
*/
